Agricultural machines towed by a tractor across a field for picking up windrowed crop material to form a cylindrical bale are commonly referred to as round balers. These machines have either a fixed or an expandable bale forming chamber defined in part by opposing vertical sidewalls. The chamber is further defined by a floor and transverse confining means comprising a continuous flexible apron and/or a plurality of transverse rolls. Frequently the apron includes an array of side-by-side belts trained around a series of rollers that extend between the sidewalls, and the floor consists of either a large roller or a continuous conveyor belt.
During field operation, crop material such as hay is picked up from the ground and fed into the chamber. The volume of crop material increases continuously in the chamber until a compact cylindrical package is formed. The package is wrapped while still in the chamber and then ejected onto the ground as a completed bale.
Round balers of the general type mentioned above comprising a chamber defined at least partially by a plurality of longitudinally extending belts supported on a series of transverse rollers have encountered problems of varying degree caused by build-up of trash on the rolls. It is not uncommon for random debris from crop material that is being formed in the chamber to pass through the spaces between the belts and becomes entrapped in the area adjacent the guide rolls or drive rolls around which the belts are traveling during operation of the baler. When the crop material being baled is damp, and particularly if it is a short cut of grass crop, an unwanted build-up of debris tends to form on the roll which is detrimental to proper belt tracking on the rollers. Eventually, if permitted to go uncorrected, various problems may occur, not the least significant of which is poor tracking which eventually can lead to binding of the belts and even eventual belt deterioration and breakage.
A number of prior art solutions to reduce or overcome these problems have been proposed. For example, U.S. Pat. No. 4,581,879, issued in the name of H. D. Anstey on Apr. 15, 1986 discloses an anti-wrap attachment for round balers directed to the avoidance of stray hay wrapping around the ends of a roll in the area of the bearings. Anstey shows a spiral element welded on a roll in combination with a scraper mounted with its edge in the vicinity of the roller to remove crop debris being carried around the surface of the roll. Scraping devices in combination with round baler rollers are also shown in various other prior art balers, e.g., U.S. Pat. No. 5,191,833, issued in the name of James T. Clevenger et al on Mar. 9, 1994, shows a stripper cooperating with a unique rigid loop structure for preventing crop debris build-up on a roller in a round baler. U.S. Pat. No. 5,408,925, issued in the name of John R. McClure et al on Apr. 25, 1995, is another example of a round baler in which apparatus is employed to discourage the build-up of unwanted trash accumulation in the vicinity of the rollers used during the formation of hay into a cylindrical bale.
Another prior art approach is the use of varying belt arrays to reduce the accumulation of unwanted debris between the belts and rollers of round balers. For example, in U.S. Pat. No. 4,707,974, issued Nov. 24, 1987 in the name of Carroll L. Harthoorn a baler using belts and rollers to form round bales shows preselected belt sections provided with a twist. In another example of prior art structure of this type, U.S. Pat. No. 4,399,746, issued Aug. 23, 1983 in the name of Jean Viaud shows a round baler in which the belts are staggered in a manner that provides openings between adjacent belts.
Various mechanisms disposed in the area where the unwanted debris accumulates have also been adapted to prior art round balers. To this end U.S. Pat. No. 5,080,009, issued Jan. 14, 1992 in the name of David P. Fritz et al, shows a mechanism for sweeping unwanted debris transversely toward an opening in the baler side wall, and U.S. Pat. No. 5,097,760, issued Mar. 24, 1992 in the name of Howard J. Ratzlaff et al shows a series of rotary elements projecting into the spaces between adjacent belts.
Although prior art arrangements for removing unwanted debris have met with varying degrees of success, there are still various crop conditions and round baler arrangements where problems caused by trash accumulation affects the overall performance. For example, in round balers having a chamber formed in part by a plurality of rollers mounted on a pivoting sledge, the limit chain for the sledge has been damaged when debris builds up between the belts and a roll controlling the position of the sledge. Thus, prevention of trash build-up without requiring elaborate modification to existing structure are interrelated aspects of reliable round baler performance to which the present invention is devoted, regardless of the chamber forming elements of the baler, or the type of crop conditions in which they operate.